1. Field of the Invention
Embodiments of the present invention relates to a liquid crystal display device, a more particularly, to a color filter substrate for a liquid crystal display device and a manufacturing method thereof.
2. Description of the Background Art
As society is becoming more and more information-driven, demand has been increasing for diverse forms of display devices. Recently, diverse flat display devices have been studied, which include a liquid crystal display (LCD) device, a plasma display panel (PDP) device, an electro luminescent display (ELD) device, and a vacuum fluorescent display (VFD) device. Some of the flat display devices are currently in use in diverse forms of equipment.
In particular, the LCD device is most widely used as a portable display device because it provides an excellent image quality, is thin and light, and consumes low-power. In light of these advantages, the LCD is supplanting cathode ray tube (CRT) as a preferred display device. For example, LCD devices are used as monitors for televisions, desktop computers, and laptop computers. To be used as a general display device, the LCD device should remain thin and light, consume low-power, but also should be able to provide a high-quality image on a wide panel that has a high definition and a high brightness.
The LCD includes a liquid crystal display panel with liquid crystal cells in an active matrix arrangement, and driving circuits for driving the liquid crystal panel. The LCD device displays images by controlling the optical transmission rate of liquid crystal cells in accordance with inputted video signals. A color image is formed on a thin-film transistor liquid crystal display (TFT-LCD) device by adjusting the optical transmission rate of an incident white light from a backlight as the incident white light propagates through the liquid crystal pixels, and additively mixing colored light emitted from red (R), green (G), and blue (B) color filter layers, which are arranged in a ratio of 1:1 on the liquid crystal pixels.
FIG. 1 shows a cross-sectional view of an LCD panel according to the related art. Referring to FIG. 1, the related art LCD panel includes a TFT substrate 10, a color filter substrate 50 and a liquid crystal material 30 injected between the TFT substrate 10 and the color filter substrate 50.
In the case of a twisted nematic (TN) type LCD panel, the color filter substrate 50 is composed of a black matrix 52, a color filter 53, an overcoat 54, a common electrode 55, and a first alignment film 56, which are sequentially formed on a transparent first insulation substrate 51. Thus, the color filter substrate 50 includes not only the RGB color filter pattern 53 for displaying colors but also an indium titanium oxide (ITO) thin film 55, which is a common electrode for applying voltage to the liquid crystal pixels, and the black matrix 52 which blocks the light between unit pixels. Also, the TFT substrate 10 may include a TFT pixel electrode 17 and a second alignment film 19 formed on a transparent second insulation substrate 11. In case of an in-plane switching (IPS) type liquid crystal display panel, both the common electrode 55 and the pixel electrode 17 may be formed on the TFT substrate 11.
FIG. 2 shows a cross-sectional view of a color mixture caused during fabrication of a color filter for the LCD panel according to the related art. Referring to FIG. 2, a black matrix 52 defining a pixel area is formed on a transparent insulation substrate 51, and a color filter 53 for displaying different colors is formed in the pixel area. The color filter uses a color photo resist (PR) including a pigment or a color ink in an ink-jet method. As shown in portion A of FIG. 2, dripping ink or color photo resist may cause an overflow in the related art method. The overflow may cause an unintended mixture of colors.